Key points are not available for this paper at this time.
Three cellular homologs of the v- erbA oncogene were previously identified in the rat; two of them encode high affinity receptors for the thyroid hormone triiodothyronine (T 3 ). A rat complementary DNA clone encoding a T 3 receptor form of the ErbA protein, called r-ErbAβ-2, was isolated. The r-ErbAβ-2 protein differs at its amino terminus from the previously described rat protein encoded by c- erbA β and referred to as r-ErbAβ-1. Unlike the other members of the c- erbA proto-oncogene family, which have a wide tissue distribution, r- erbA β-2 appears to be expressed only in the anterior pituitary gland. In addition, thyroid hormone downregulates r- erbA β-2 messenger RNA but not r- erbA β-1 messenger RNA in a pituitary tumor-derived cell line. The presence of a pituitary-specific form of the thyroid hormone receptor that may be selectively regulated by thyroid hormone could be important for the differential regulation of gene expression by T 3 in the pituitary gland.
Hodin et al. (Fri,) studied this question.